Prior reserve forming devices have included an auxiliary thread guide disposed pivotably in front of the rotating bobbin tube (German Auslegeschrift No. 2 543 986, FIG. 1). In this case, formation of the reserve windings is claimed to be ended by pivoting of the auxiliary thread guide in the direction of the center of the tube. The auxiliary thread guide must be located close to the bobbin tube so that the thread catching projection provided on the bobbin tube can receive the thread from the auxiliary thread guide. There is a risk, on pivoting of the auxiliary thread guide, of the guide coming into contact with the thread catching projection which leads to damage to these parts.
To avoid this disadvantage, the method has been proposed of arranging the thread guide in front of the bobbin tube in such a way that it is not moved parallel to the surface of the bobbin tube (German Auslegeschrift No. 2 616 965). The thread reserve is formed from the thread extending from a yarn delivery point to the thread guide. Due to its tension the thread travels in the direction of the center of the tube until the traversing thread guide receives it and forms regular windings. Control of the length of the thread reserve is hence not possible.